A medium dose of UVA1 phototherapy does not diminish vitamin D level in patients with atopic dermatitis

Introduction
Medium-dose UVA1 phototherapy is a widely used method in treatment in patients with atopic dermatitis. There are suggestions that UVA1 can decrease cutaneous production of vitamin D via photodegradation.

Objective
To determine whether a medium dose of UVA1 phototherapy decreases serum concentration of vitamin D in patients with atopic dermatitis.

Material and methods
The study included 21 patients with atopic dermatitis. A serum concentration of calcidiol (25(OH)D) was measured at the start and end of 20-day medium-dose UVA1 phototherapy: one exposure daily from Monday to Friday, with increasing doses of 10 J/cm2, 20 J/cm2, 30 J/cm2 and 45 J/cm2.

Results
Phototherapy with UVA1 significantly reduced the SCORAD index (p < 0.001), extent of skin lesions (p < 0.001) and subjective symptoms (p < 0.001). A serum concentration of 25(OH)D negatively correlated with the SCORAD index before UVA1 phototherapy (r = –0.57; p < 0.05). The serum concentration of 25(OH)D did not differ before and during the course of phototherapy. The recommended level of vitamin D before UVA1 phototherapy was found in 5 (23.8%) patients, whereas insufficiency in 4 (19%) and deficiency in 12 (57.2%) patients with atopic dermatitis.

Conclusions
A medium dose of UVA1 phototherapy does not diminish the serum concentration of 25(OH)D in patients with atopic dermatitis. There is a need for further research on a larger group of individuals to confirm these findings.